Projectile driving band



Oct. 17, 1944. w. e. cALKlNs iROJECTILE DRIVING BAND Filed March 5, 1938 IN VENTOR UflLK/N. I 2124 W.

WILL/AM a. Y fi A TTORNEKS.

Patented Oct. 17, 1944 PRQJECTILE DRIVING BAND William G. Calkins, Detroit, Mich., assignor to Chrysler Corporation, Highland Park, Mich, a

corporation of Delaware Application March 3, 1938, Serial No. 193,699

4 Claims.

This invention relates to improved projectile driving bands and method of forming and mounting the same on projectiles.

More particularly, the invention pertains to the provision of projectile driving bands comprising porous metal bearing surfaces and having a substantial absorbed lubricant content.

. One of the main objects of the invention is to provide an improved projectile driving band which has a steel back reinforcing portion that is conveniently securable to the body portion of a projectile and an external lubricant impregnated, sintered, porous metal element bonded thereto and having a surface engageable with the barrel of a gun.

Another object of the invention resides in the provision of a method for manufacturing projectile driving bands which have a lubricant impregnated porous metal barrel engaging portion.

Additional objects of the invention are to provide a projectile driving band of this character which lubricates the passage through a gun barrell of the projectile by which it is carried, as well as subsequent projectiles, without depositing harmful quantities of lubricant in the gun; to provide a projectile driving band which carries a charge of liquid lubricant in its interior and which has external surfaces that are substantially free from lubricant wetted areas.

' Additional objects of the invention are the provision of a, porous metal lubricant containing element as a projectile band which may be produced economically in sheet-like formation and conveniently integrally bonded to an attaching member which is readily securable to a projectile; and to provide a porous metal lubricant containing element of this kind which will withstand stripping by the rifiing or by the tapering of a gun barrel during high muzzle velocity discharge of projectiles as well as the severe conditions of temperature and pressure incident to such muzzle velocities.

Other objects and advantages of the invention will bemore apparent from the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a side elevational View, partly in section to disclose the underlying structure, of a projectile embodying the invention.

Fig. 2 is an enlarged vertical sectional view taken as indicated by the line 2-2 of Fig. 1.

Fig. 3 is a vertical sectional View taken approximately as indicated by the line 3--3 of Fig. 2..

' Fig. 4 is a side elevational view corresponding to Fig. 1 but illustrating a modified form of the invention.

Fig. 5 is a fragmentary sectional view of the portion of the projectile within the circle designated by the numeral 5 in Fig. 4.

Fig. 6 is a fragmentary, sectional view of a projectile having a driving band embodying a further development of the invention.

In the form of the invention illustrated in the drawing, the improved projectile driving band, generally designated by the numeral I0, is illustrated in Figs. 1 to 3 as being non-rotatably secured to a projectile II. The illustrated projectile is adapted to be fired from a rifled gun barrel and may carry two driving bands, but preferably only one is employed in order that the projectile may be used in barrels having gain-twist rifling. The projectile II has a reduced portion I2 in which are formed a pair of spaced, annular grooves I3 having substantially less width than and being located adjacent the extremities of the reduced portion I2. 7

The driving band includes a steel reinforcing ring I5 having a pair of inwardly extending lugs I6 and is split at H. The ring I5 is substantially as wide as the reduced portion of the projectile on which it is snugly fitted. The outer edge portions 2'! of the ring which overlap the grooves I3 are preferably formed to fit into the latter.

The ring I5 has suitably bonded to its outer surfacea layer of lubricant impregnated, sintered porous metal bearing material I8. The split ends of the ring I5 are suitably secured together, as by welding.

' In mounting driving bands of this character on a projectile, the reinforcing ring and its porous metal layer are drawn around the reduced portionI 2 prior to deformation of the marginal edge portions with the lugs I6 disposed in recesses formed in the reduced portion I2 and the split ends of the ring I5 are welded together as illustrated at I9. After the driving band I0 is mounted on the projectile, each of the edge portions of the steel ring I5 is deformed, as by spinning at 21, into one of the grooves 53 so as to assist in preventing relative longitudinal movement between the driving ring I!) and the projectile II. The deformed marginal portions of the ring I5 may be welded to the projectile at circumferentially spaced locationsas indicated at I9.

In the manufacture of sheet porous metal stock for driving bands of this character a powdered metal charge is preferably formed into a continuous, sheet-like briquette by passing it through rolls in accordance with the disclosure in my taneously sinter the briquettes and weld the resuiting porous metal to the sheet steel. If desired, the briquettes may be sintered in a non-oxidizing or reducing atmosphere and then applied to the steel backing and subsequently bonded thereto by heating under the above described conditions.

It has been found that both sheet briquettes and the finished sheet porous metal formed from the following compositions possess the characteristics desired during the period of manufacturing driving bands and in the finished product. The porous metal has a substantial lubricant absorptive capacity and may be readily impregnated with lubricant by immersion therein while hot or cold or in any suitable manner. The pores of the porous metal ring may be supplied with a charge of lubricant which is normally in either liquid or solid state at atmospheric conditions. The conditions of temperature and pressure existing during firing of projectiles may in many instances be relied upon to force the lubricant to the outer periphery of the bearing ring.

7 Percent by weight Powdered lead 1'0 Powdered tirn Powdered graphite 1 Powdered boric acid 1 Powdered copper -e 77 Per cent by weight Powdered tin 10 Powdered boric acid Exfoliated mica 1%; Powdered copper 88 Per cent by Weight Powdered copper Powdered graphite 1V Powdered boric acid 1 Powdered iron 77.5

Referring now to Figs. 4 and 5. wherein is illustrated a somewhat slightly modified embodiment of the invention, it will be understood that this modified arrangement is intended'to be substituted for the corresponding parts previously described and shown in Figs. 1 to 3. It will be noted that the projectile 20 has but one driving band, generally indicated by the numeral 2|, this projectile being adapted to be fired from a gaintwist gun barrel. This projectile 20 is provided with a reduced trailing end portion 20' and a pair of spaced annular grooves 22, one located at the forward extremity of the reduced end portion and the other between this location and the trailing end of the projectile. The driving band includes a steel reinforcing ring 23 adapted to closely surround theireduced portion '20 and of suflicient width to. extend into both grooves 22 and slightly beyond the rear groove. The ring 23 has suitably bonded thereto a lubricant impregnated, sintered, porous metal bearing ring 24. The respective parts of the driving band shown in Figs. 4 and 5 may be formed and bonded together in accordance with the procedure herein set forth or in any suitable manner and after applying the band to the projectile in the position illustrated the end portions 25'of the reinforcing ring are preferably swedged or spun into the grooves 22 and the extremities of this ring may be welded, as indicated at 26, to the body portion of the projectile. The outer periphery of thev porous metal rings 24 and I8 of each form of the invention respectively extends outwardly, sufiiciently beyond the outer surface of the projectile to engage the barrel surface during firing.

The projectile 4|, shown in Fig. 6 of the drawing, is provided with a driving band 40, comprising the foregoing type of porous bearing metal and it also has a. substantial, self-contained lubricant content. The band 40 may be applied to a suitable cylindrical portion of the projectile M by wrapping a sheet-like strip of porous bearing metal around the projectile and bonding it directly to the outer surface, or through the medium of a suitable bonding metal, during a heat treatment of substantially the same character as that recommended for bonding such material to a reinforcing backing. This 7 direct bondingof the band to the projectile may take place before or after sintering the compressed powdered metals of which the porous bearing metal is formed and if bonded prior to the sintering operation the latter operation and the bonding will be;accomplished simultaneously;

The band may then be charged with lubricant in any suitable mannenas for example, by heat ing the projectile and band'slightly and im mersing them in'oil.

Various modifications and changes may be effected in the illustrated applications without departing from the spirit of the invention or the scope of the appended claims.

What I claim is: s a

1. A driving band for projectiles having a. re-

duced annular portion provided with a; pair of spaced relatively deeper annular grooves, comprising a sheet metal reinforcing ring adapted to fit closely a-roundsaid' reduced projectile portion. and having end portions extending over said grooves, and a layer of porous metal bearing material comprising mainly a uniformlyforaminous mass of unfused particlesof metal v fixed together by fused bonds having a lower melting point than that of said metal particles saidlayer being bonded byjthe metal thereof directlyto prising a sheet metal reinforcing ring adapted content, said end portions of said ring being adjacent said body and with edge portions therecrimped into said grooves, and means including of disposed over said grooves, and pressing said a lug on said ring seated in a slot in said proedge portions into said grooves.

jectile for holding said driving hand against ro- 4. A driving band for a projectile having tation relative to said projectile. 5 spaced circumferential grooves in its main body 3. In the manufacture of a projectile; the portion said band including a cylindrical sleeve l method of providing thereon a driving band comprising deformable solid metal, and a layer which includes forming spaced annular grooves of porous metal bearing material comprising a in a cylindrical portion of the body of said procompressed and sintered uniformly foraminous jectile, surface bonding to all but the opposite 10 mass of powdered metal particles fixed to the marginal portions of a strip of sheet solid metal, external surface of said sleeve by direct bonds a layer of porous bearing metal comprising a between the latter and said particles and excompressed mass of unfused powdered metal tending axially of said sleeve over all but the particles fixed together by bonds comprising end marginal portions thereof, the end marginal metal of a lower melting point and provided with 15 portions of said sleeve being disposed over said a substantially absorbed liquid lubricant content, grooves and crimped into the latter for retaining disposing said strip and said layer around said said driving band in place.

body with an entire side surface of said strip WILLIAM G. CALKINS. 

